Speaker
Mr
Vasily Kudryavtsev
(BINP, NSU)
Description
The VEPP4-M collider has a unique system for energy measurement based
on Resonance Depolarization technique. The existing system is working
well using the Touschek effect for measurement of polarization at the
energies below 2 GeV. For higher energies it is suggested to use the
effect of asymmetry of reflected polarized laser photons
back-scattered from polarized beam. For the measurement of
polarization degree of the beam the coordinates of compton scattered
photons are registered with different polarization of the laser. Since
non-polarized beam does not produce asymmetry, thus difference in mean
coordinate yields the information about polarization degree of the
beam.
For registering of coordinates of reflected photons the special
gaseous detector with triple-GEM was manufactured. The readout
structure is a rectangular grid of 1120 pads, which are 2x1 mm sized
in center and 4x2 mm on the edge where bigger pads are used for a
rough alignment of the detector. In front of sensitive area the lead
convertor is placed which converts the reflected photons into charged
particles registered by the detector. The trigger for the detector,
which is the same signal fed to laser, is generated by frequency
division of VEPP4-M bunch crossing signal and is in the range of 1-4
kHz while the laser polarization can be switched on every flash. For
the gathering of signals from the pads of the readout structure the
DMXG64 front-end ASICs, which were developed at BINP, are used.
The prototype detector was tested and the principle was proved. The
final detector is assembled and first results will be presented at the
conference.
Summary
The Laser Polarimeter is being developed at VEPP-4M collider for beam energy
calibration by Resonant Depolarization technique. The essential part of this facility is a photon-tracking detector measuring coordinates of backscattered gammas. The final detector is assembled and first results will be presented at the conference.
Primary author
Mr
Vasily Kudryavtsev
(BINP, NSU)
Co-authors
Dr
Ivan Nikolaev
(Budker Insitute of Nuclear Physics)
Mr
Lev Shekhtman
(Budker Institute of Nuclear Physics)
Prof.
Nikolai Muchnoi
(Budker INP SB RAS)
Dr
Sergey Nikitin
(BINP)
Viacheslav Kaminskiy
(Budker Institute of Nuclear Physics SB RAS)
Dr
Vladimir Blinov
(BINP)
